Process for the manufacture of benzimidazoles having higher alkylgroups at the u-carbon atom



Patented Feb. 18, 1936 STATES PATENT PROCESS FOR THE MANUFACTURE OF BEN- ZIMIDAZOLES HAVING HIGHER. ALKYL- GROUPS AT THE ,u-CARBON ATOM No Drawing. Application May 14, 1934, Serial No. 725,654. In Switzerland May 18, 1933 Claims. It is known that benzimidazoles having higher alkyl-groups at the ,u-carbon atom can be made by'heating ortho-phenylenediamine with a saturated fatty acid, such as butyric acid, caproic acid, lauric acid, palmitic acid or stearic acid (compare Seka, Monatshefte fiir Chemie (1931), Vol. 57, page 99).

In specification Ser. No. 667,133 it has been shown that the cyclic amidines which, on the one hand are derived from orthoor 1:8-arylenediamines and on the other hand contain as a substituent at the i-carbon atom an aliphatic residue containing at least 3 carbon atoms, may be used as parent materials for making valuable textile assistants.

This invention relates to a process of making cyclic amidines which does notnecessitatethe use of the isolated fatty acids but condenses the arylene-diamines with natural fats or other fatty acid glycerides, cyclic amidines or valuable mixtures of cyclic amidines being obtained.

As parent materials for the invention there are suitable the glycerides of the various fatty acids, both of lower and higher fatty acids. Aslower fatty acids there come into consideration inter alia those from triacetine andtributyrine (the glycerides of acetic acid and butyric acid), the glycerides of propionic acid, valerianic acid, capronic acid, oenanthylic acid, caprilic acid, pelargonic acid etc., or also the glycerides of the unsaturated acids which-correspond to the above acids. Particularly valuable initial materials are those from higher aliphatic acids, i. e. acids containing 10 or more carbon atoms, such as caprinic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and the like, or the corresponding unsaturated acids with one or more double bonds, such as oleic acid, linoleic' acid, linolenic acid, clupanodonic acid, ricinolic acid, and so forth. Further valuable starting materials arethe natural products known as oils and fats, there being suitable both the relatively saturated fats, such as coco-butter, palm kernel oil, beef tallow, mutton tallow, or the like, and fats with comparatively high iodine numbers, such as olive oil, castor oil and linseed oil. The

last-named fats yield chiefly mixtures of cyclic amidines, which contain a long aliphatic unsaturated side chain at the l-carbon atom. Finally, there are also suitable the hydrogenated fats, the

so-called hardened fats, such as hardened fish oil; these may advantageously beused for making mixtures of cyclic amidines.

As 1,2- or 1,8-arylenediamines suitable for the condensation, there may be named ortho-phenylene-diamine, its homologues and analogues, for instance ortho-toluylenediamine, 1,2-naphthylene-diamine and 1,8-naphthylenediamine. Further, products such as N-mono-methyl-orthophenylenediamine, N-mono-ethyl-ortho-phenylenediamine, N-monobenzyl-ortho-phenylenediamine, ortho-aminodiphenylamine, 2-amino-1- phenylnaphthylamine, and so forth.

The cyclic amidines obtainable according to the present process therefore correspond to the general formula wherein 2: stands for a ring of the benzene or naphthalene series which, by means of two adjacent carbon atoms, the term adjacent comprising atoms in orthoor peri-position, is directly linked to the two nitrogen atoms, R1 stands for a fatty radical, and R2 for hydrogen, alkyl, aralkyl or aryl.

For obtaining light colored products the condensation of the fat with the arylenediamine should occur with as much exclusion of oxygen as possible, and preferably in the presence of a small proportion of reducing agent, such as a salt of sulfurous acid, aluminium borings or the like. When a highly unsaturated fat is to be used for the condensation, the fat is preferably heated for a short time in an atmosphere free from oxygen or in a vacuum in presence of a small proportion of a reducing agent, such as aluminium borings, before it is mixed with the arylenediamine.

The use of fatty acid glycerides in making the cyclic amidines renders it possible in a single operation simultaneously to reduce an aromatic nitroamino-compound and to condense the diam:

is possible in this manner to obtain directly saturated cyclic ,u-alkyl-amidines. Production of saturated highly alkylated cyclic amidines which contain at the ,c-carbon atom higher alkyl groups is of course also practicable when starting from the orthoor peri-diamines and unsaturated fats, and conducting the condensation in presence of a suitable catalyst, for example finely subdivided nickel, in an atmosphere of hydrogen.

The glycerin which is liberated in the condensation may be distilled in a vacuum or separated from the molten product by washing with water; however, the mixture may often be further worked up without separating the glycerin.

The mixtures of cyclic amidines made according to the invention are, according to the kind of parent material, colorless to yellow-brown fatty substances, with various melting points; for example, the benzimidazole from ortho-phenylenediamine and coco-butter is a solid mass with a crystalline structure. If olive oil be substituted for coco-butter, there is obtained a semi-solid, salve-like mass, and from castor oil there is obtained a highly viscous oil.

The following examples illustrate the invention, the parts being by weight:-

Example 1 Into 280 parts of coco-butter (saponification -No.-258), contained in a suitable stirring vessel and heated to 120-l40 C. in a current of nitrogen, there are distilled in the current of nitrogen 140 parts of ortho-phenylenediamine. After parts) is, when cold, a feebly yellowish crystalline, solid mass and consists, when the glycerin has been distilled in a vacuum to the extent of about 95 per cent., of benzimidazole having higher'alkyl-groups at the l-carbon atom. The melting point of the product is 65 C.; the saponification No. is 15.

Example 2 Into 1920 parts of hardened fish oil (saponification No. 185-190: iodine No. 10-15), 650-660 parts of ortho-phenylenediamine are distilled in themanner described in Example 1, whereafter the mixture is heated to 230-240 C. until no further phenylenediamine can be detected therein. The product (about 2400 parts) solidifies when sation there may also be obtained a product whose saponification N0. is 0-2. Its solidifying point is Example 3 320 parts of olive oil (saponification No. 190) are heated, while stirring, in a suitable vessel containing an atmosphere of nitrogen, with 10 parts of aluminium borings for half-an-hour to two hours at ZOO-220 C. There are then distilled into this pretreated oil 110 parts of ortho-phenylenediamine and the mixture is heated in a current of nitrogen at 220-240 C. until no more phenylenediamine can be detected in a sample of the mass.

' The product (about 400 parts) is a clear oil, which is yellow when hot, but at room temperature is a yellowish salve-like mass. The saponi- "fication N0. is 12.

Example 4 330 parts of castor oil (saponification No. Q,. 5). are heat for h fz nrh o 2 ho at ZOO-220 C., while stirring, in a suitable vessel and in a slow current of nitrogen, with 5 parts of a finely powdered anhydrous sodium sulfite.

There are then distilled into the oil thus obtained 320 parts of raw linseed oil (saponification No. 189-190) are heated for half-an-hour to 2 hours at ZOO-220 C., while stirring in a suitable vessel and in a slow current of nitrogen, with 5 parts of aluminium borings. There are then distilled into the oil at a temperature of l-l85 C. 110 parts of ortho-phenylenediamine and themixture is heated in a current of nitrogen at'220- 240 C., until a sample no longer shows the presence of phenylenediamine.

The product (about 400 parts) is a yellowish solidifies at room temperature to a soft crystalline mass. The saponification No. is 12.7.

Example 6 Into a suitable hydrogenating autoclave provided with an upright condenser and a receiver for condensation water, there are charged-218 parts of coco-butter (saponification No. 257) 138 parts of ortho-nitraniline and- 5-10 parts of nickel catalyst. The mixture is heated, while" stirring with anefficient stirrer under a pressure of hydrogen of 4-10 atmospheres, at -l00 C., whereby a vigorous absorption of hydrogen sets oil with a slight milky turbidity when warm; it

in. When, at C., no further absorption of hydrogen can be observed, the mass is heatedunder a low hydrogen pressure of l-5 atmospheres to ZOO-220 C., and the condensation is carried to an end at this temperature, namely until no phenylenediamine can be detected in the product. ner by hot filtration or centrifuging from the catalyst and washed with hot dilute sodium carbonate solution. It is a mixture of benzimidazoles (about 280 parts) which solidifies at ordinary temperature to a crystallinemass and con tains only 2-3 per cent; of fatty acids.

The procedure may also be such that the reduction of nitroaniline proceeds at -90-100 C.

and after completion of the hydrogen absorption the hydrogen is blown off and the condensation carried to an end in a slow current of inert gas at atmospheric pressure.

Example 7 with 47.4 parts of 1:8-naphthylenediamine for--24 hours in a slow current of nitrogen at 240 C., whereupon no more naphthylenediamine can be detected in the product. The latter (about 32 arts of coco-butter (saponification No. 258) are heated with 22 parts of 1:2-naphthylenediamine in a current of nitrogen for 15 hours at The-latter is then freed in known man- 96 parts of hydrogenated fish oil are heated" parts) consists of a mixture of glycerine and e 'amlne is to be detected in the mixture. The product (about 45-50 parts) is a light colored mass, viscous in the cold, from which, by redissolution and reprecipitation, there is obtained a mixture of 1:2-naphthimidazoles containing higher alkylgroups at the -carbon atom.

In all these examples natural products have been used. The method of working is exactly the same if instead of the fats and oils cited in the examples there are used the corresponding quantities of the other glycerides named in the first part of paragraph 4 of this specification. There may also be used mixed glycerides or mixtures of glycerides.

What I claim is:-

1. A process for the manufacture of benzimidazoles of the general formula wherein R1 stands for a higher alkyl radical dontaining at least 9 carbon atoms, consisting in condensing ortho-phenylenediamine with a glyceride of such a higher fatty acid which contains at least 10 carbon atoms, the condensation being can'ied out in the presence of a reducing agent.

2. A process for the manufacture of benzimidazoles of the general formula EI XR.

wherein R1 stands for a saturated higher alkyl radical containing at least 9 carbon atoms, consisting in condensing ortho-phenylenediamine with a glyceride of such a saturated higher fatty acid which contains at least 10 carbon atoms, the condensation being carried out in the presence of a reducing agent.

3. A process for the manufacture of benzimidazoles of the general formula wherein R1 stands for a saturated higher alkyl radical containing at least 9 carbon atoms, consisting in condensing ortho-phenylenediamine with coco-butter, the condensation being carried out in presence of a reducing agent.

5. A process for the manufacture of benzimidazoles of the general formula wherein R1 stands for a saturated higher alkyl radical containing at least 9 carbon atoms, consisting in condensing ortho-phenylenediamine with olive oil, the condensation being carried out in presence of a reducing agent.

' CHARLES GRAENACHER.

FRANZ ACKERMANN. 

